*{margin: 0;
    padding: 0;}
    body,html{
      width: 100%;
      background: #f0f0f0;
      
    }
 
    
    /* 头部 */
    body,html{
      width: 100%;
      color: #f0f0f0;
    }
    #top{
      width: 100%;
      height: 40px;
      background: #2d2d2d;
      position: fixed;
      overflow: hidden;
      z-index: 10;
     
    }
 